Paragraph Structures in Scientific English

In previous articles we have looked at linking paragraphs, linking sentences, and how to write sentences in Scientific English. These articles have had a common theme: structure. This article is also part of that series, focusing on the two types of paragraph structures in Scientific English.

What is a paragraph? Why does it need a structure?

Have you ever read a paragraph without a structure? Sentences are just thrown in, there are no connections between anything, and it feels like a chaotic hostage situation. Who knows what will turn up and who is going to get hurt in the process? Most importantly, it is extremely difficult to read and comprehend. On the contrary, a paragraph with well-defined paragraph structures is much easier to read. It also means that people are more likely to put in the time to understand what you wrote if they aren’t wasting energy.

When we talked about sentences, we were looking at the smallest unit of scientific writing. In some ways, we can relate what we know from sentences to paragraphs. However, paragraphs are a bit more complex. Where a sentence represents a single idea, a paragraph represents a topic or a theme. Miriam-Webster Dictionary defines a paragraph as “a subdivision of a written composition that consists of one or more sentences, deals with one point or gives the words of one speaker, and begins on a new usually indented line”.

While a paragraph is more complex than a sentence, the number of ways to structure paragraphs effectively is actually lower than for sentences. Parts of sentences can move around a lot but the information in cohesive paragraphs can only be presented in two ways:

Point-First paragraphs

The first way to present information at the paragraph level is the point-first paragraph. In a point-first paragraph, you make a strong statement for your topic statement (i.e. the first sentence or two). Afterwards, you develop this idea by adding supporting information, which acts to back up the statement you made at the beginning.

If you would like to compare this paragraph structure with the structure of an overall article, it is most like the OCAR structure.

Let’s look at an example:

We wish to put forward a radically different structure for the salt of deoxyribose nucleic acid (5). This structure has two helical chains each coiled round the same axis (see diagram). We have made the usual chemical assumptions, namely, that each chain consists of phosphate diester groups joining beta-D-deoxyribofuranose residues with 3′,5′ linkages. The two chains (but not their bases) are related by a dyad perpendicular to the fibre axis. Both chains follow right-handed helices, but owing to the dyad the sequences of the atoms in the two chains run in opposite directions (6) . Each chain loosely resembles Furberg’s2 model No. 1 (7); that is, the bases are on the inside of the helix and the phosphates on the outside. The configuration of the sugar and the atoms near it is close to Furberg’s “standard configuration,” the sugar being roughly perpendicular to the attached base. There is a residue on each every 3.4 A. in the z-direction. We have assumed an angle of 36° between adjacent residues in the same chain, so that the structure repeats after 10 residues on each chain, that is, after 34 A. The distance of a phosphorus atom from the fibre axis is 10 A. As the phosphates are on the outside, cations have easy access to them.
Watson and Crick’s controversial publication on DNA: A Structure for Deoxyribose Nucleic Acid

This quote comes from one of the most well-known articles of all time, the controversial Watson and Crick publication that did not credit Rosalind Franklin for her work. Watson and Crick’s article favoured the point-first paragraph structure. This paragraph starts with the main argument in the first paragraph: a radically new, different structure. Everything afterwards simply supports this idea, tying back into that first sentence.

Point-last paragraphs

The second way to present information at the paragraph level is the point-last paragraph. This is where you start simply at the beginning and build up towards the end, revealing the main point of the paragraph. Generally in this structure, you start with something that the reader knows already (e.g. common knowledge or something you wrote earlier in the article) and add to it. You then end the paragraph with the thing you really want the reader to know: the golden nugget of information.

If you would like to compare this paragraph structure with the structure of an overall article, it is most like the OCAR structure.

Let’s look at an example:

Salvage logging is an increasingly common way of harvesting forests that have been attacked by insect pests. In salvage logging, trees that have been attacked are selectively harvested. The dead trees that are harvested, however, can provide cavities that are nesting sites for birds. The population biology of cavity-nesting birds is therefore likely affected by salvage logging.

What is the topic in this paragraph? In point-last paragraphs, the main idea is always at the end. While the focus of the paragraph seems to be logging, the most important information is that cavity-nesting birds are affected. This paragraph helps the reader to understand salvage logging and what it does, then goes into how that would affect these birds.

Point-First vs Point-Last Paragraph Structures

So how do you know which type of paragraph to use? There are a couple of factors we need to consider:

What does the reader already know?

The main difference between a point-last paragraph and a point-first paragraph is how much you think your reader can handle. Do they have enough information to understand the point you want to make? Do they need a bit of help to get there?

If they need help, that means you need to build your argument. Of the two paragraph structures, the one that does that the best is the point-first paragraph. A point-first paragraph holds the reader’s hand, guiding them and giving them the information they need to be able to understand the main point.

Can the reader understand the main point of the paragraph without needing to be shown the way? Then the point-first paragraph works the best. They get the information immediately and don’t have to worry about going through the entire paragraph to get to that point.

But how do I know if they know the information or not? If you are writing in a specialist journal and the information they need to know is common knowledge among those specialists, they don’t need a helping hand. A point-first paragraph is perfect for this.

But what if it is a complex concept, it took me a while to understand this from my own research, or it is not an obvious outcome/conclusion? This is an excellent case for the point-last paragraph. If you had some difficulties, then it is likely that people who did not do the same research will also need some help to understand. Help them by using a point-last paragraph, guiding them by showing the path or reason/deductions/experiments you took to come to this conclusion.

Where am I in my article?

At certain points in articles, you are more likely to find one paragraph structure over another. For example, the materials and methods section almost only uses point-first paragraphs. They often start with “To do X, we …”. This is an example of starting with a strong topic sentence (i.e. the entire reason why this paragraph exists). Everything after this sentence is helping the reader to follow how the researcher(s) did this experiment. On the flip side, the discussion section almost exclusively uses point-last paragraphs. Since you need to explain your conclusions (and can’t assume the audience is following the same train of thought as you), explaining things in a point-last paragraph helps take readers on the same path of logic and reasoning that you went down.

What if I can’t change my paragraph to point-first or point-last?

If you have tried to change your paragraph to follow one of these paragraph structures and you haven’t been able to, there are some things you can ask yourself:

What is the point of this paragraph?

If it is trying to make multiple points, break it into multiple paragraphs. Each paragraph should only have one point. Look at each sentence and see which point it belongs to. Once you have organised them by point, combine them into new, smaller paragraphs. At this point, it should be more obvious how each should be structured. Afterwards, go through these and look at linking on the sentence and paragraph levels.

The reader can probably understand most of my argument but there is a bit they might not be able to. What should I do?

If the reader can easily understand something, there is no reason to explain it in great detail. However if part of the information puzzle is missing, then you need to use a point-last paragraph. This will give them the information they need to understand the point. For the rest that they do understand, you do not need to belabour the point by going into minute detail. That just wastes both your time and their time. Instead, reduce that to a level where they understand the reference.

Practise fixing a bad paragraph

The following is an example of a bad paragraph. Identify the ideas that are presented in the paragraph. Should they be in the same paragraph? Hint: no

Adding compost to soil promotes microbial growth, which then increases microbial production of phosphatase enzymes that release plant-available P from organic matter. Bromus carinatus is a native grass that can be used in re-establishing California grasslands. Its success in P-poor systems can be stimulated by inoculation with mycorrhizal fungi. However, the effects of mycorrhizal inoculation of B. carinatus on P uptake have not been assessed.

This paragraph is like a small hostage situation. There are several topics in this paragraph:

P availability to growing plants
Restoring degraded California ecosystems
Two approaches are possible: add compost, mycorrhizae
B. carinatus can be used to reestablish grassland
Effects of B. carinatus are unknown

As a result, these should be either in separate paragraphs or, if they do actually relate to each other, structured in such a way that presents the information that way.

How would you write/re-write these paragraphs? Which of the paragraph structures would you use? Feel free to put your ideas in the comments below.

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